The patent specification for the wire race bearing lists its advantages in detail – and later ensures the successful development of the company through licence revenues.
The documented history of the wire race bearing (at the time of its invention usually still referred to as a “wire race ball bearing”) began with patent no. 625 461 from the Reichspatentamt [former Patent Office of the German Reich] dated 23rd January 1936, in which an invention patented on 3rd March 1934 was made public. The subject of the invention was “a ball bearing in which [...] the raceways of the balls consist of four open rings of steel wire that are embedded directly in the rotations of the two bodies supported on each other by the bearing”.
The patent was issued to “Carl Zeiss in Jena”. However, the wire race ball bearing was invented by Erich Franke, who had been working as a design engineer at Zeiss since 1922. He wanted to avoid the disadvantages of the ball bearings made of hardened steel rings that had been used up to that point: Especially with large-diameter bearings, the steel rings need very thick walls to prevent stresses during machining and hardening from having a negative effect on the finished bearing. Other disadvantages are the different expansion coefficients of the rings and the surrounding body, the required installation space and the complex manufacturing process. His invention, often referred to colloquially as the “Franke bearing”, was different: It combined high running accuracy and smooth running through uniform force absorption – and this with significantly lower space requirements and largely free choice of material for the surrounding body. It could be manufactured more cost-effectively and could also lead to cost savings in the manufacture of the supported body due to the low space requirements.
It is not known when and how Franke first developed the idea for this revolutionary invention. What is certain, however, is that his superior at Zeiss, Prof. Dr Walther Bauersfeld, provided him with substantial support in the theoretical calculations. He was regarded as the inventor of the modern projection planetarium – and it stands to reason that the idea for the wire race ball bearing was born in this context. However, it was guaranteed that Erich Franke would share financially in the fruits of his invention. This was also because the “Franke bearing” quickly became a sought-after product for defence technology, for example for rangefinders, periscopes and gun mounts.//
Ingenious design meets scientific brilliance: The mechanical engineer and physicist Prof. Dr Walther Bauersfeld provided the comprehensive theoretical calculations for Erich Franke's invention and published the 28-page "Theorie der Drahtkugellager nach Franke [Theory of wire race bearings according to Franke]" around 1940.